1. Technical Field
The present invention relates to a fast handover system and a method thereof, more specifically to a fast handover system and a method thereof that can minimize the handover latency when a mobile communication terminal moves in an environment of PMIPv6 mechanism.
2. Description of the Related Art
With rapidly increasing Internet users, there has recently been growing interests in the mobility of Internet service that attempt to access Internet in moving positions as well as fixed positions by using mobiles.
In the Internet, an Internet protocol (IP) address having a network identifier and a host identifier is assigned to a host. The host makes the connectivity with other hosts by using the assigned IP address. Accordingly, when the host makes and maintains the connectivity with other hosts, the IP address must be constantly maintained. If the IP address is changed, the previous connectivity will he disconnected and a new connectivity will be made.
When the Internet is used in fixed positions, the IP address is rarely changed. In contrast, if the Internet is used in moving positions, the previous connected network and the network identifier may move to other networks. At this time, a new IP address is assigned to the network identifier in other networks, and thus the host is required to make a new connectivity. This causes the service to be interrupted.
To solve the above problem, a mobile IP (MIP) was suggested, which can support the mobility of a mobile node (MN) via a home agent (HA) and a foreign agent (FA). Also, a mobile IPv6 (MIPv6) was suggested, which can support the mobility of an MN in IPv6.
The MIPv6 is developed for the mobility of the IPv6. In order to enable an MN to he moved, it is required to bind a home address (HoA) and a care of address (CoA) of the MN through the signaling between the MN and HA. The signaling between the MN and HA can be performed by adding an MIPv6 client function into the IPv6 stack of the MN. However, it is necessary to provide the IP mobility, regardless of the MIPv6 function, in consideration of the MNs having no MIPv6 function.
It is possible to support the mobility of the IPv6 MN by expanding the signaling in the MIPv6 by use of a proxy mobility agent (PMA) located at the network and by re-using the HA. Such method of supporting the mobility allows the MN not to involve in the signal exchanging process for managing the mobility. The PMA located at the network performs the MIPv6 signaling and manages the mobility instead of the MN. This method is called PMIPv6 because the existing MIPv6 signaling and the HA function are used as it is or expanded.
In the typical PMIPv6 mechanism, two mobile access gateways (MAG) involving in the handover of an MN exchange the signaling for setting the fast handover. The MAG is coupled to an access link in order to manage the signaling related to the mobility of the MN. The MAG also is the entity that monitors whether the MN is attached to the access link and performs the signaling with local mobility anchor (LMA) instead of the MN. At this time, two MAGs can share security association (SA) to protect a signaling message related to the fast handover. In this case, all MAGs are required to share the SA regardless of whether to be adjacent to each other. This has an effect on the state of each MAG related to the SA.